50 



FARMER'S CYCLOPEDIA OF LIVE STOCK 



supply the body with energy. The most 

 convenient measure of the potential en- 

 ergy of a food is the amount of heat 

 evolved from it when it is completely 

 oxidized or burned. 



The unit of heat measurement is the 

 calorie. A calorie of heat is the amount 

 required to raise the temperature of a 

 pound of water 4° F. The energy value 

 of a feeding stuff is based on the amount 

 of the ration that is digestible. A 

 pound of digestible protein is estimated 

 to have a fuel or heat value of I860 

 calories. A pound of digestible fat has 

 a heat value of 4220 calories; while a 

 pound of digestible carbohydrates has 

 the same heat value as a pound of di- 

 gestible protein, 1860 calories. The total 



plied is available for other work such as 

 chewing and digestion of food, drawing 

 a load, etc. 



The energy of food i s first employed 

 in carrying out these functions, after 

 which it appears as heat, just as when the 

 energy of the hammer in motion is 

 converted and appears as heat in the 

 iron. The food nutrients are not first 

 converted into heat and then into other 

 forms of energy as fuel is in the engine. 

 The heat is the final result of the va- 

 rious forms of energy exercised in the 

 body. It is a waste or excretory product 

 and is eliminated from the body in sev- 

 eral different ways. It is only when this 

 source of heat is not sufficient to meet 

 the demands of the body for heat that 



Fig. 36 — IN THE MIDST OF THE OATS HARVEST 



fuel value of a feeding stuff is found by 

 using all these factors. 



This heat unit of measurement, the 

 calorie, is employed as a matter of con- 

 venience and not because the primary 

 function of food is to supply heat. This 

 is not the case. The food is used pri- 

 marily to supply energy. The energy is 

 used first of all in the necessary muscu- 

 lar and other work of the internal or- 

 gans, as the circulation of the blood 

 respiration, maintenance of the elas- 

 ticity of the muscles, the processes of se- 

 cretion, absorption, excretion, osmosis, 

 nerve and brain work, etc. The surplus 

 energy existing after these requirements 

 for the vital activities have been sup- 



food materials are oxidized for the 

 special purpose of keeping the body 

 warm. 



Net energy—Work of any kind uses 

 up energy and results in the production 

 of heat. In eating and digesting food 

 much more heat is evolved from the 

 body than when the animal is at rest. 

 The more difficult the food is to masti- 

 cate and digest the greater is the amount 

 of energy expended. 



Coarse foods are not nearly so well 

 adapted to rapid gains as concentrates 

 because of the greater energy required 

 to eat and digest them ; even though they 

 contain an equal quantity of nutrients. 

 Armsby found that a steer fed timothy 

 hay utilized 37 per cent of the energy 



